Loud Clicking noise coming out of the tank

[Pinchy]

Originally Posted by globaldesigns

I have those sounds also... Come and goes. Usually lots of clicks, then nothing for awhile (weeks or months) then it starts up again for awhile, usually in the evenings, when the lights are out.

Based on this comment it is definitely a mantis shrimp. Impossible to catch, i had to tear my tank apart to get mine out. This was the sole reason i bought marco rock for my new 72 bow and used the rest of the old live rock in the sump..